Eczemas due to mites and microorganisms ROBERT JACKSON,* MD, FRCP[C] Eczema is a specific clinical, products) may cause eczema (Table II) Under the microscope it may be more morphologic and microscopic reaction and to discuss what is known about difficult to find spongiosis or vesicula- pattern of the skin. It has many the mechanisms involved. tion because biopsy material allows one causes, including external and internal The term eczema, derived from the to examine only a small area at one chemicals and the action of various Greek word meaning to boil over or stage of the eruption. microorganisms - bacteria, fungi, erupt, describes a reaction in the skin Physicians trained in observation can yeasts, viruses and mites - and their and certain adjacent mucosae. It is construct a retrospective or prospective products. Peripheral vesicles with characterized by a series of gross le- picture so that they can say of a non- undermined borders are a feature of sions and histologic changes, as sum- vesicular eruption that it may have had all eczemas caused by fungi, yeasts marized in Table III. In some eczema- at one time, or it may develop, vesicles. and bacteria and are thus a useful tous eruptions one or more of these At times one cannot be certain. diagnostic finding. findings may be present at any one time, to the apparent exclusion of some Bacterial eczema L'eczema represente un sch6ma of the others. The fundamental lesion r6actionnel cutane cliniquement, of eczema is the vesicle (Fig. 1) or the Many patients with eczema have a morphologiquement et microscopi- spongiotic intercellular edema (Fig. 2) quement specifique. II y a plusieurs that produces the vesicle; unless this causes, y compris certains agents is present at some stage or in some area chimiques externes et internes et the eruption cannot be called eczema. l'action de divers microorganismes - bact6ries, fongus, levures, virus et acares - et de leurs sousproduits. Des v6sicules peripheriques aux contours profonds sont caracteristiques de tous les eczemas causes par les fongus, les levures et les bact6ries et constituent donc un element diagnostique utile. Eczema is a common multiform reac- tion pattern in the skin caused by numerous and varied external and in- ternal stimuli (Table I). The purpose of this paper is to point out that dif- ferent types of microorganisms (or their FIG. 1-Eczema on dorsum of hand: large number of small crusted vesicles. ,;4. * ,, *Dermatologist, Ottawa Civic Hospital; assistant professor of medicine (dermatology), University of Ottawa To be presented to the Ottawa Bacteriological FIG. 2.-Acute eczema: intercellular Club Feb. 10, 1977 edema of epidermis (spongiosis) and ex- Reprint requests to: Dr. R. Jackson, Ste. 508, tensive intraepidermal vesiculation (hema- 1081 Carling Ave., Ottawa, Ont. K1Y 4G2 toxylin-eosin; x250, reduced 50%). 156 CMA JOURNAL/JANUARY 22, 1977/VOL. 116 large number of bacteria growing in The favourable response to systemic eroded surface with a peripherally un- the eczematous area and in the normal antibacterial therapy reported (anecdot- dermined border (Fig. 6). This form adjacent skin, although the contents of ally) for some cases in the last two characteristically occurs in warm, the initial intact vesicle may be sterile. groups has implicated bacteria as being moist, body folds (for example, pen- Patch tests with autogenous broth cul- important in the cause of these types anal, genitocrural and inframammary tures or filtrates of Staphylococcus of eczema. This response, however, is areas and fingerwebs), especially in per- aureus (or with mixed bacterial cul- by no means always assured. sons with a deficient immune system. tures) show a strongly positive reaction, Often there are satellite vesiculopustules as manifested by areas of eczema be- Yeast eczema decreasing in number and size the neath the patch. Exacerbation of the farther they are from the primary inter- primary focus of eczema may be seen One form that infections of the skin triginous eruption. The earliest histo- after intracutaneous or subcutaneous due to Candida a)bicans can take is pathologic changes are localized spon- injection of an autogenous or mixed that of numerous small vesiculopustules giotic areas in the upper epidermis, vaccine. Some widespread eczemas, that coalesce to form a red, glistening, usually just below the stratum corneum, such as exudative "seborrheic" bacterial eczema, respond promptly to the ad- ministration of systemic antimicrobial agents. Storck1 reported that the eczemato- genic agent in bacteria is a protein that can act as an antigen without acquiring a protein linkage with the epidermis. Loewenthal,2 however, considered that it was also possible (and perhaps more likely) for the spread of eczema to be due to autosensitization of a patient to his skin, which is not uncommon when large numbers of bacteria are present; in this case the bacteria would join with some epidermal protein (the protigen of Epstein.) and cause the release of anti- genic epidermal protein into the blood stream, with subsequent development of eczema in distant areas. The long-claimed relation between foci of infection in such areas as the teeth, tonsils, sinuses, gallbladder and prostate has never been proven and is still based primarily on anecdotal re- ports. How do these findings relate to clin- FIG. 3-Pustular eczema with peripheral ical disease? The most obvious and undermining on amputated thumb with FIG. 4-Coccal eczema in lower portion clear-cut* bacterial eczemas are those underlying osteomyelitis. of retroanricular crease. that appear in areas of skin bathed continuously in pus discharging from, for example, the middle ear, an osteo- myelitis sinus or a leg ulcer. When the source of the pus is cleared up the eczema disappears (Fig. 3). All forms of true bacterial eczema are now rare, owing presumably to the widespread availability and use of antibacterial drugs to treat the underlying chronic purulent infection. Another type is the sharply margin- ated eczema with vesicles and pustules and a peripheral undermined border without any obvious underlying source of discharging pus. These were more common on the hands and fingers and had such names as dermatitis repens and acrodermatitis continua (Fig. 4). A third group consists of eczemas that present as discrete, coin-shaped erythematous plaques studded with small vesicles, usually on the legs, arms or forearms (nummular eczema) (Fig. 5). Clinical experience indicates that severe dryness (as produced by over- zealous washing with soap) is probably '1 H(.. 5-Nummular eczema on leg; bright FIG. 6.-Interdigital candidiasis with un- an important causative factor. red lesions. dermined border. CMA JOURNAL/JANUARY 22, 1977/VOL. 116 157 which rapidly fill with polymorpho- 4. Failure to demonstrate fungi in nuclear leukocytes and serum.4 A filt- the secondary lesion. ered, sterile, phenol-treated extract of 5. Spontaneous clearing of the sec- disintegrated Candida cells (oidiomy- ondary eruption when the primary le- cm) reproduces typical cutaneous can- sion subsides, whether spontaneously or didiasis when applied to the skin as following treatment. a patch test. This reaction is mediated by an endotoxin-like substance released As with oidiomycin, skin testing with by organisms on the surface of the trichophytin (a filtered, sterile extract skin. Opinion varies as to whether the of phenol-treated fungus culture) is not spongiotic pustules are produced by the much help in diagnosing fungal infec- direct action of this substance or by tions. Apparently most of us are at an antigen-antibody reaction. Intra- some time exposed to the allergenic dermal injection of oidiomycin gives a components, so many persons will have positive tuberculin response in most pa- a positive test result even though they tients because most adults have been do not have an active fungal infection. exposed either to these fungi or to Patch testing with some trichophytin microorganisms with similar antigenic extracts may produce an eczematous or allergenic structures (hence, cross- reaction.7 The allergic constituents are reaction occurs). polysaccharides.8 Jones, Reinhardt and Rinaldi9 re- Fungal eczema cently did intradermal testing with a FIG. 8-Delled papules of molluscum purified trichophytin preparation, re- contagiosum. There are several types of superficial corded the number of patients showing fungal infections of the skin that are delayed sensitivity, and correlated this months or years. A perilesional halo of blistering and closely mimic the gross with the number of patients showing eczema about 5 to 10 cm in diameter morphologic and the histologic features clinical and cultural evidence of derma- develops in about 10% of patients," of nonparasitic eczemas5 (Fig. 7). tophytosis. Their data suggested that though not all the lesions in a patient One type is tinea cruris (eczema patients showing positive delayed sensi- will show this eczema. The eczema may marginatum), which has an arcuate tivity to trichophytin were immune and occur on adjacent touching body parts; vesicular border with undermining of those with a negative test result were for example, molluscum contagiosum the epidermis at the periphery. The susceptible to chronic fungal infections. with perilesional eczema on the inner central portion has a tendency to heal, Cruickshank, Trotter and Wood" aspect of the arm can produce eczema with slight scaling and browning and passively transferred trichophytin sensi- on the lateral chest wall where the af- sometimes lichenification. The genito- tivity in guinea pigs by means of pen- fected area of the arm touches it. Pre- crural, intergluteal and perianal areas toneal cells and, in so doing, estab- sumably, because not all the lesions are the sites of predilection. Epider- lished that the cell-mediated immune cause an eczema, the process is local; mophyton floccosum is one of the system is responsible for these delayed- also, because the eczema is transferable fungi causing this condition. type reactions. by contact, the eczematogenic sub- Blistering tinea also can produce ec- stance must be water-soluble.